Find the number of following reactions which are involved in roasting process :
(i) `S_(8) + 8 O_(2) overset (Delta)rarr 8SO_(2) uarr`
(ii) `P_(4) + 5O_(2) overset (Delta) rarr P_(4) O_(10) uarr`
(iii) `4 As + 3O_(2) overset (Delta) rarr 2 As_(2) O_(3) uarr`
(iv) `2ZnS + 3 O_(2) overset (Delta) rarr 2 ZnO + 2SO_(2) uarr`
(v) `ZnCO_(3) overset (Delta) rarr 4 ZnO + CO_(2) uarr`.

Explanation

To solve the question regarding the number of reactions involved in the roasting process, we will analyze each of the given reactions step by step.

### Step 1: Understand the concept of roasting
Roasting is a metallurgical process that involves heating an ore in the presence of oxygen. The main purpose of roasting is to convert the ore into its oxide form. Therefore, we need to identify which of the given reactions involve the conversion of a substance into its oxide with the involvement of oxygen.

### Step 2: Analyze each reaction

1. **Reaction (i)**:
\[ S_{8} + 8 O_{2} \overset{\Delta}{\rightarrow} 8 SO_{2} \]
- This reaction involves sulfur reacting with oxygen to produce sulfur dioxide (SO₂).
- **Conclusion**: This is a roasting reaction.

2. **Reaction (ii)**:
\[ P_{4} + 5 O_{2} \overset{\Delta}{\rightarrow} P_{4}O_{10} \]
- Here, phosphorus reacts with oxygen to form phosphorus pentoxide (P₄O₁₀).
- **Conclusion**: This is also a roasting reaction.

3. **Reaction (iii)**:
\[ 4 As + 3 O_{2} \overset{\Delta}{\rightarrow} 2 As_{2}O_{3} \]
- In this reaction, arsenic reacts with oxygen to produce arsenic trioxide (As₂O₃).
- **Conclusion**: This is a roasting reaction.

4. **Reaction (iv)**:
\[ 2 ZnS + 3 O_{2} \overset{\Delta}{\rightarrow} 2 ZnO + 2 SO_{2} \]
- Zinc sulfide (ZnS) is oxidized in the presence of oxygen to form zinc oxide (ZnO) and sulfur dioxide (SO₂).
- **Conclusion**: This is a roasting reaction.

5. **Reaction (v)**:
\[ ZnCO_{3} \overset{\Delta}{\rightarrow} 4 ZnO + CO_{2} \]
- This reaction involves the thermal decomposition of zinc carbonate (ZnCO₃) to produce zinc oxide (ZnO) and carbon dioxide (CO₂).
- **Conclusion**: This is not a roasting reaction, as it does not involve oxygen in the reactants.

### Step 3: Count the roasting reactions
From the analysis:
- Reactions (i), (ii), (iii), and (iv) are roasting reactions.
- Reaction (v) is not a roasting reaction.

Thus, the total number of reactions involved in the roasting process is **4**.

### Final Answer
The number of reactions involved in the roasting process is **4**.

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